Idaho’s climate is diverse, with several different climate zones crossing through the state. Curiously, despite the state’s distance from the Pacific Ocean, Idaho’s weather is still moderated by it. This gives it some interesting climate features. If you’re looking for the best weather in Idaho, I’m about to give several suggestions on where you can find it.
Because there’s no single definition of what “best weather” means, I’m going to cover a few cities in Idaho: cities with warm weather, cities with mild weather (including with the mildest winters and the mildest summers), and cities with the coldest weather for those who enjoy winter sports.
What City in Idaho Has the Best Weather Year Round?
Because Idaho is a rather cold state, I consider the best weather year round as weather that’s the warmest and the sunniest (even if that includes hot summer months).
Lewiston in northern Idaho across the river from Clarkston in Washington state is the warmest city of the state. In my ranking of the warmest cities in Idaho, it’s up to a few degrees warmer than an average Idaho city.
The average winter temperature in Lewiston reaches 41-47 °F during the day and 30-32 °F at night. On the warmest winter days Lewiston may experience temperatures of up to 56-59 °F. The coldest nights may bring temperatures of 15-18 °F. Lewiston records on average 11 snowy days with 12.7 snowfall inches per year which is one of the lowest amounts in Idaho.
The average summer temperature in Lewiston reaches 79-91 °F during the day and 54-61 °F at night. There are only two months of hot weather with an average temperature around 90 °F (July and August). The hottest summer days may reach 96-104 °F while the coolest summer nights may drop to 44-51 °F.
There’s no data on sunshine hours for Lewiston but there’s data on how many days of rain it gets. On average, there are 106 precipitation days and almost 13 inches of rain per year.
The only drawback of Lewiston for some is that the area is not as populated as Treasure Valley or southern Idaho in general.
For other options in the Pacific Northwest, read my article What Are the Warmest Cities in the Pacific Northwest?
What City in Idaho Has the Mildest Weather?
If you’re looking for the most temperate climate in Idaho, my assumption is that you want the warmest winters possible but also the coolest summers possible.
Since this is often difficult to get in the same city, I have two suggestions. One is a city that has the warmest winter and a slightly warmer summer. The second suggestion is a city with slightly cooler winters but also cooler summers. You pick which option is best for your preferences.
Best Winter Weather in Idaho With Still Mild Summers
For the best winter weather, Lewiston is still the best option. Considering it has only two months with average temperatures above 90 °F, it’s still a mild weather city for Idaho standards.
The winter months in Lewiston, with daytime temperatures well above freezing (41-47 °F), are much more temperate than in other cities in the state. While nighttime temperatures do go below freezing (30-32 °F), Lewiston is still much warmer than the second warmest city in Idaho, Boise (Idaho’s capital city).
Boise experiences winter daytime temperatures of 39-46 °F and 25-29 °F at night. And in the summer it’s slightly hotter, with highs of 81-93 °F and lows 54-62 °F (as opposed to 79-91 °F and 54-61 °F in Lewiston).
Glenns Ferry has warmer winter days than Lewiston. The average temperature between December and February is 44-50 °F. But Glenns Ferry has colder winter nights and much hotter summers with average temperatures climbing to 99 °F in the hottest month (definitely not mild anymore).
Best Summer Weather in Idaho With Still Mild Winters
If your idea of the best average summer temperature is as cool as possible (but still without extremely cold winters), then one of the best mild weather cities in Idaho for you is Coeur d’Alene.
If you look at the city’s average temperature and compare it to the coldest and warmest cities in Idaho, Coeur d’Alene will be roughly in the middle.
Winter temperatures range from 36 to 41 °F during the day and 26-27 °F at night. The warmest days may bring temperatures of 49-51 °F while the coldest nights may get very cold, with temperatures of 10-14 °F. Still, these are relatively mild winters for the state, particularly considering average high temperatures above freezing.
With 16 snowy days and 27.8 inches of snowfall a year, Coeur d’Alene has four distinct seasons, albeit still relatively mild ones.
In exchange for cooler winters than in Lewiston, the city offers much more pleasant months between June and August. Summer temperatures range from 72 to 83 °F during the day and 51-57 °F at night. Mean maximums may climb to 89-96 °F while mean minimums may drop to 42-48 °F.
Coeur d’Alene gets 122 precipitation days with 25.35 inches of rainfall a year which is twice the amount of rain falling in Lewiston.
The small town of Cottonwood in north-central Idaho has even cooler summers with temperatures of 69-79 °F during the day and 48-55 °F at night. But it has colder winters, with average highs of 35-40 °F (1 degree cooler than in Coeur d’Alene) and lows of 23-26 °F (3 degrees colder than in Coeur d’Alene).
What City in Idaho Has the Coldest Weather?
If you want to live in Idaho because you don’t like hot weather and/or want the longest winter season possible for skiing and other winter sports, then look no further than Sun Valley and Ketchum. These two towns, functioning almost as one, have by far the coldest weather in Idaho.
Average winter temperatures in the area are between 30-35 °F during the day. They drop to very cold 8-11 °F at night. The warmest winter days don’t bring much warmth, heating up to 43-47 °F. The coldest nights can bring extreme conditions, with subzero temperatures around -7 to -9 °F.
Being able to enjoy outdoor activities in the snow is arguably one of the main reasons why people live in the area. With 38 snowy days and 102 snowfall inches a year, there’s no shortage of fresh white powder. First snowfall may appear in October already, while the last snowfall is usually in April.
Summers in Sun Valley and Ketchum are pleasant. Average highs climb to 70-80 °F while average lows drop to 40-45 °F. The warmest summer days bring temperatures of about 84-90 °F while the coldest nights can drop to or near freezing to 29-35 °F.
The closest alternative to Sun Valley and Ketchum is McCall. It has more snowfall, recording 51 snowy days and 132.2 snowfall inches per year. It has slightly warmer winters and summers, though.
Frequently Asked Questions
Because of the rain shadow effect due to the mountains in Washington and Oregon, most of Idaho gets little precipitation and is dry.
Mountain Home is one of the least snowy places in Idaho. It gets 7 snowy days and 10.3 snowfall inches.
Some cities in Idaho have relatively cool summers with average high temperatures between 75-85 °F and average lows of 50-60 °F. Examples include Coeur d’Alene, Twin Falls, and Rexburg.
While the coldest cities in Idaho do have harsh winters with freezing temperatures and lots of snow, the largest cities don’t have harsh winters. Nights do fall below freezing but daytime temperatures are above freezing.
Mountain Home is one of the driest places in Idaho. It gets 73 rainy days and 10.55 precipitation inches.
Idaho Falls is much colder in the winter than Boise, with temperatures lower by at least 10 degrees. The hub for Eastern Idaho is cooler in the summer than the capital, though, with temperatures lower by about 5-6 degrees.
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